Refers to the chalk line drawn around a corpse in movies. The 'line' idea is mostly fictional, since it contaminates the crime sceneinvestigation, but it serves as more dramatic metaphor for murder.
When a woman with a fatherless child tries to get a new guy to be the new father within a few weeks of dating. He's getting 'fast-laned' into a family he didn't start.
"Mikey's only been with her a month and the kid's calling him 'Dad'. I think he's getting fast-laned!"
"Andy nobody in our gan digs movies and books the way I do. For a while there, I thought I was the only person in the world that did. So I loned it."
-The Outsiders, S.E. Hinton